one-dark/gtk-3.0/sass/ui/entry.scss

$vert_padding: 5px;
//
// Text Entries
//
entry {
  border: 1px solid;
  padding: 5px 8px;

  caret-color: currentColor;
  border-radius: 3px;
  transition: all 200ms $ease-out-quad;

  &.search {
    border-radius: 4px;
  }

  @include entry(normal);

  image {
    // icons inside the entry
    color: mix($fg_color, $base_color, 80%);

    &.left {
      padding-left: 0;
      padding-right: 5px;
    }
    &.right {
      padding-right: 0;
      padding-left: 5px;
    }
  }

  &.flat {
    &,
    &:focus {
      padding: 2px;
      @include entry(normal);
      border: none;
      border-radius: 0;
    }
  }

  &:focus {
    background-clip: border-box;
    @include entry(focus);
  }

  &:disabled {
    @include entry(insensitive);
  }

  selection {
    &:focus,
    & {
      @extend %selected_items;
    }
  }

  @each $e_type, $e_color, $e_fg_color in (warning, $warning_color, $warning_fg_color),
    (error, $error_color, $error_fg_color),
    // entry.search-missing for Gnome-Builder
    (search-missing, $error_color, $error_fg_color)
  {
    &.#{$e_type} {
      color: $e_fg_color;
      border-color: $entry_border;
      background-color: mix($e_color, $base_color, 60%);

      image {
        color: $e_fg_color;
      }

      &:focus {
        color: $e_fg_color;
        background-color: $e_color;
        box-shadow: none;
      }
      selection,
      selection:focus {
        background-color: $e_fg_color;
        color: $e_color;
      }
    }
  }

  &:drop(active) {
    &:focus,
    & {
      border-color: $drop_target_color;
      box-shadow: none;
    }
  }

  .osd & {
    @include entry(osd);
    &:focus {
      @include entry(osd-focus);
    }
    &:disabled {
      @include entry(osd-insensitive);
    }

    selection {
      &:focus,
      & {
        color: $selected_fg_color;
        background-color: $selected_bg_color;
      }
    }
  }

  progress {
    margin: 0 -6px;
    border-radius: 0;
    border-width: 0 0 2px;
    border-color: $selected_bg_color;
    border-style: solid;
    background-image: none;
    background-color: transparent;
    box-shadow: none;
  }

  // linkded entries
  .linked:not(.vertical) > &,
  .linked:not(.vertical) > &:focus {
    @extend %linked;
  }

  .linked.vertical > &,
  .linked.vertical > &:focus {
    @extend %linked_vertical;
  }
}

treeview entry {
  &.flat,
  & {
    border-radius: 0;
    background-image: none;
    background-color: $base_color;

    &:focus {
      border-color: $selected_bg_color;
    }
  }
}